MERCURY

By Greenpeace Mercury is the familiar silvery liquid found in thermometers. When exposed to air, liquid mercury evaporates easily into mercury vapor. Mercury vapor can be inhaled and absorbed into the bloodstream. Mercury compounds are even more dangerous. Paints, anti-mildew agents, electrical equipment, and batteries contain inorganic mercury which is easily converted by bacteria into the far more hazardous organic forms of mercury. Methylmercury is the best known of these forms. It is readily concentrated by fish and other aquatic organisms, increasing in concentration (biomagnifying) in higher levels of the food chain, including humans. Certain carnivorous fishes, such as the northern pike, can accumulate mercury at levels 10,000-100,000 times the concentration in surrounding waters.

Exposure to mercury results primarily from inhalation of mercury vapor or eating food contaminated with methylmercury. Mercury is found in greatest concentrations near mines, smelters, solid waste incinerators, and fossil fuel plants. Workers and people living near these facilities may be exposed to greater than average mercury levels. In Alaska, cinnabar ore mines and retorting sites have leached mercury into the environment. Acidification of surface waters by acid rain may increase levels of methylmercury in the environment. Global warming and ozone depletion may lead to greater levels of mercury in freshwater fishes, by increasing levels of mercury deposition and rate of conversion to methylmercury.

Mercury is capable of causing severe brain damage in developing fetuses and nervous system damage in children and adults. The expression "mad as a hatter" comes from the mental disorders that occurred in workers who made felt hats, a manufacturing process that once used mercury. Mercury also suppresses the immune system. Our next issue will contain more information on contaminants, submissions welcome.

Excerpted from the Green peace 1996 Community Toxic's Conference materials